Tuesday, September 23, 2008

The challenge of assisted sustain, making Gary's brain explode





Allen our wonderful man of many hats and blogmaster has been in and out of town so I (Gary) have been at it.
Today I had to make EMG pickups work with a Fernandes sustainer.
Owners send me these tasks from far and wide and I'm not a stranger to them. Recently Gibson hired me as a consultant to assist in the prototyping of the Neal Schon guitar ( a very cool Les Paul with a Sustainer, Floyd Rose and smoothed out neck heel joint).

Always learning!!!!

Here we have to combine a sustainer with an EMG 81 and an EMG SA pickup in the neck of a Neal Schon Les Paul. The challenge: according to the fine instructions included with the sustainer you simply hook it up as shown and you're off and running. Well, that's okay if you like low pitch oscillation creeping in while playing in the sustain mode and a deafening high pitched squeal. Our solution: install a filter to decouple the power supply between the sustainer and the EMG pickups (sharing the same power supply made them oscillate to distraction). There were a few other options but this turned out to be the most stable (and we could get away with using one battery). Result: Low rumble & squeal gone!!!!

Other tweaks, mods, etc. involved in this particular job: I tried padding the EMG signal going into the circuit to make it a little more like the passive signal it expects but I found a better idea. I added a trim pot to to the gain circuit so we have the ability to further turn down the gain of the sustain. Since the drive was much higher with the active pickup input there was plenty to spare. Here are some work in progress pics. On Fernandes's behalf they do state how difficult it is to use the sustainer circuitry in applications that stray from how it was originally intended to be used (and that we did!). I'm glad they now make it available, because there was a time they would not sell sustainers outside of the guitars they built since it is so difficult an installation. There are also a few other Sustainer products on the market that in some ways are easier to install and work great. I will go over them in the future.

Always a big thanks to our friend: Doc K.R.!!!

4 comments:

Mike said...

WOW....thats preety full on,ive installed the fsk 401,Emg 81 and Emg AB and have the same problem in high mode, it starts to occilate...is that the right word?anyhow i cant use that mode other 2 a fine...got any quick fix ideas?

Gary Brawer Guitar Repair said...

why yes....contact us!

go to: www.brawer.com for contact information.

Malius said...

Hey, is the oscillation a problem when using just a 81, without the added single coil?

I'm wondering as I'm having a guitar made with a Sustainer and an 81, which Fernandes offer. However the manufacturer has said active pickups don't seem to provide a good sustain with the sustainer. I really want my 81 in there so any help would be more than appreciated!

Gary Brawer Guitar Repair said...

Using a separate battery for each circuit will almost always cure that problem of crosstalk. Gary